another another wired article about the topic:
excerpt:
"...Self-trackers seem eager to contribute to our knowledge about human life. The world is full of potential experiments: people experiencing some change in their lives, going on or off a diet, kicking an old habit, making a vow or a promise, going on vacation, switching from incandescent to fluorescent lighting, getting into a fight. These are potential experiments, not real experiments, because typically no data is collected and no hypotheses are formed. But with the abundance of self-tracking tools now on offer, everyday changes can become the material of careful study.

When magnifying lenses were invented, they were aimed at the cosmos. But almost immediately we turned them around and aimed them at ourselves. The telescope became a microscope. We discovered blood cells. We discovered spermatozoa. We discovered the universe of microorganisms inside ourselves. The accessible tools of self-tracking and numerical analysis offer a new kind of microscope with which to find patterns in the smallest unit of sociological analysis, the individual human. But the notion of a personal microscope isn't quite right, because insight will come not just from our own numbers but from combining them with the findings of others. Really, what we're building is what climate scientist Jesse Ausubel calls a macroscope.

The basic idea of a macroscope is to link myriad bits of natural data into a larger, readable pattern. This means computers on one side and distributed data-gathering on the other. If you want to see the climate, you gather your data with hyperlocal weather stations maintained by amateurs. If you want to see traffic, you collect info from automatic sensors placed on roadways and cars. If you want new insights into yourself, you harness the power of countless observations of small incidents of change—incidents that used to vanish without a trace. And if you want to test an idea about human nature in general, you aggregate those sets of individual observations into a population study.

The macroscope will be to our era of science what the telescope and the microscope were to earlier ones. Its power will be felt even more from the new questions it provokes than from the answers it delivers. The excitement in the self-tracking movement right now comes not just from the lure of learning things from one's own numbers but also from the promise of contributing to a new type of knowledge, using this tool we all build..."